(a) Field of the Invention
The present invention relates to a micropump and a driving method thereof. More particularly, the present invention relates to a valveless micropump and a driving method thereof.
(b) Description of the Related Art
With the development in the micromachining technology, research on microdevices, such as micro-electro mechanical systems (MEMS), has been actively conducted. In the devices, a micropump, a device that manipulates a very small amount of fluid using fluid mechanics, is applied to various fields, including medical chemistry systems and medical equipment, such as chemical analyzing systems and medicine delivery systems, as well as inkjet heads.
When a mechanical valve is adopted to operate the micropump, a friction force for interfering with a normal valve operation is provided because of a fluid characteristic in a microchannel condition. For example, a flow of fluid in a microsystem is very low so it depends on viscosity which is substantially influenced by a change of temperature.
Therefore, a valveless micropump with a long lifespan and great reliability free from the friction force without a mechanical valve is required to be developed.
The valveless micropump is represented by a device for periodically compressing a pincher in an elastic tube to generate a flow, or a device for installing a nozzle action unit and a diffuser action unit in both ends of a pump case in which a piezoelectric actuator is installed and controlling the same to function as a valve.
However, the valveless micropump for generating the flow by periodically compressing the pincher into the elastic tube generates the flow according to a pressure difference caused by superposition and offset phenomena of a pressure wave in the elastic tube, and it is difficult to precisely control the flow rate and generate a large pump pressure because of the above-noted complicated principle of generation.
Also, the valveless micropump with a nozzle action unit and a diffuser action unit installed at both ends of the pump case has a complicated manufacturing process since both the nozzle action unit and the diffuser action unit must be installed at both ends of the pump case.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.